Process of extracting sulfur from ores.



Patented lune 26, 1900.

J. S; FLEMING & H. FROEHLBNG.

PROCESS UFEXTRAGTING SULFUR FROM GRES. (Application led June 16, 1899.)(N0 Model.)

W/TNESSES 4 www@ me nanars Evans ca, FnuTcLLnHo., WASHINGTON b c am am ATTOHNE YS 'NITED STATES Pn'rnrvr l llOHN SYME FLEMING AND HENRYFROEHLING, OF RICHMOND, VIRGINIA.

PROCESS OAF EXTRACTING SULFUR FROM ORES.

SPECIFICATION forming part of Letters Patent No. 652,672, dated June 26,IQO. Application filed Tune 16, 1899. Serial No. 720,865. (Nospecimens.)

To all whom, t may concern:

Be it known that We, JOHN SYME FLEMING and HENRY FRoEHL1NG,citizens ofthe United States of America, and residents of Rich'- mond cit-y, in theState of Virginia, have invented certain new and useful Improvements inProcesses of Extracting Sulfur from Orcs, of which the following is aspecification.

Our invention relates to improvements in the old process of separatingsulphur from iron pyrites and from iron and copper pyrites bydistillation.

By the old process of distillation of sulphur from iron pyrites onlyone-half of the sulphur contained in the ore could be separated. This isthe amount of sulphur which is theoretically separable in a free statefrom the ore by distillation in a properlyarranged apparatus withoutaccess of air, and this action is expressed by the equationFeSzzFeS-l-S, in which one part of iron pyrites, consisting of one atomof iron and two atoms of sulphur, gives up one atom of its sulphur andretains the second atom of sulphur in combination with the iron ,formingsulphide of iron. However,when the separa-tion of sulphur from ironpyrites by the old process of distillation is conducted on a large scalethe ore rarely yields more than sixteen per cent. of the containedsulphur. By the admission of air, which contains oxygen, to thedistilling apparatus them combination of the atom of iron with thesecond atom of sulphur in the'sulphide of iron was broken, and thesulphur was separable, not in a free state, but in the form of sulphurdioxide, and in order to recover the sulphur from the sulphur dioxide itwas necessary to subject the latter to further treatment by other andseparate processes The object of our invention is to overcome thesedisadvantages in a simple manner and to separate from thesulphur-bearing ore a larger percentage of sul phurin an uncombinedstate than is separable by the process of distillation as heretoforeconducted; and it consists in separating sulphur from sulphur-bearingores by heating the ore in an atmosphere consisting of a gas or gaseswhich are not supporters of combustion, such as carbon dioxide ornitrogen or a mixture of both, and the addition of a small and regulatedquantity of oxygen. .As in the old process, so in our improved process,about one-half of the conf tained sulphur can theoretically be separatedby distillation; but by our improved process we can, by conducting theoperation of distilling the ore in an atmosphere consisting of a gas orgases which are not supporters of combustion, such as carbon dioxide ornitrogen or a mixture of both, and by admitting into the receptaclewhich contains the ore a small and regulated quantity of oxygen, theamount of oxygen admitted to the receptacle being determined as statedhereinafter, separate a further quantity of sulphur in a free state.

In'the accompanying drawing, Which forms a part of this specication, isshown a form of apparatus, partly in section and partly in elevation,adapted for use in the practice of our improved process.

Ve do not limit ourselves to the exact form and details of constructionof the apparatus as shown in the drawing, which is used only to renderclear the description of the manner in which We put our improved processinto operation.

Referring to the drawing, 1 is a retort i adapted to contain the oreundergoing treat ment and set in a furnace having a grate 2 and a stack3.

et 5 represent a pipe leading from the stack 3 and adapted to conductfrom the stack the products of combustion arising from the grate 2.

10 is a damper situated in the stack 3.

6 and 7 are pipes connected with the interior of the retort 1, and 9 isa pipe connecting the interior of the retort 1 with the collectingchamber or condenser 10.

.8 is a steam-pipe connected with the interior of the pipe 9.

11 11 are bafiieplates placed in the upper part of the condenser 10 andhaving openings 21.

12 is a pipe connecting the condenser 10 with a scrubbing-tower 13.

13 is a scrubbing-tower containing broken limestone 19 and connected atits upper end with a water-cistern 14, which has the perforated pipe 15,adapted to allow a gentle stream of water to iiow from the cistern 14down into the scrubbing-tower 13. At its IOO the tank.

The manner in which we put our process into practice is as follows: Weplace the sulphur-bearing ore in the retort 1, which is' heatedexternally by the lire in the grate 2, in which either` coke or coal canbe burned. As soon as the temperature of the ore Within the retort israised sufficiently sulphur will be given off, and this action willcontinue until about one-halt' or the first equivalent of the sulphurcontained in the ore is set free, leaving the remaining one-half orthesecond equivalent of sulphur in combination with the iron of the ore,forming sulphide of iron. At about this time We pass in'to the retortthrough the pipe 6 a gas or mixture of gases which are not supporters ofcombustion, such as carbon dioxide or nitrogen or a mixture of both,Which when coke is the fuel burned in the grate 2 can be extracted fromthe stack 3 through the pipe 4 5 or can be derived from independentsources. A su fficient quantity of these gases should be admittedthrough therpipe 6 to keep the retort 1 and the coudenser 10 full. Wethen admit to the retort 1 by means of the pipe 7 the small quantity ofoxygen or air necessary for the successful Working of our'process, asexplained hereinafter. A reaction takes place which We believe to be oneor the other of the following: First, the admitted oxygen combinesdirectly with the iron of the sulphide of iron, forming oxides of iron,`and the sulphur of the sulphide of iron is set free in an nncombinedstate; second, the admitted oxygen combines with the sulphur of thesulphide of iron to form oxides of sulphur, which oxides are immediatelyreduced by the iron, with the formation of oxides of iron, the sulphurbeing set free in an uncoinbined state; but whether one of these is oris not the reaction which takes place we get oxides of iron and sulphuris set free in au uncombined state.

The amount of oxygen admitted and its rate of admission to the retortwill necessarily depend upon the class of ore treated ,upon the size ofthe charge, and upon the rate at whichl the process is worked and shouldbe such a quantity as shall be sufficient to oxidize the iron of the oreforming the charge and, as far as we know, no more.

Now in practice on a large scale and under ordinary working conditionsand taking into consideration the various grades of the different orestreated and the varying rate of progress of the operation it is notalways practicable to so regulate the stream of admitted oxygen -or airthat it shall be correctly proportioned tothe quantity of iron in thecharge, nor under similarconditions is it always practicable to preventthe ingress of air through leaks in the apparatus-that is to say, it isnot always practicable under ordinary Working conditions to avoid theloss by oxidation of some part of the sulphur contained in or separatedfrom the ore. Therefore when conducting our process on a large scale weconnect with our condenser a scrubbing-tower 13, in which we fixWhatever oxides of sulphur may be produced, any formation of which fromthese causes can be detected at a cock attached to the pipe 12,whereupon the'quantity and the rate of admission of the oxygen or aircan be readjusted.

Now the sulphur which is separated from the ore in both the primary andsecondary stages ofour improved process is for the most part in a stateof extremely-fine division, a fact which renders its condensation andcollection diflicult and slow. WVe therefore in practice insert asteam-nozzle 8 in the pipe 9 or in the condenser 10. The steam admittedat this nozzle has the effect of causing the sul phur to condense morerapidly and in a creamy or semiliquid state.

Having now described our improved process for the separation of sulphurfrom sulplruiu bearing ores, what we claim, and desire to secure byLetters Patent of the United States, 1s

Process of obtaining sulphur from sulphurbearing ores which consists ofsubjecting the ore to'distillation in an atmosphere consisting of gas orgases which are not supporters of combustion, but with the admixture ofa controlled quantity of oxygen substantially as described.

Signed by us at Richmond city, Virginia, this 13th day of June, 1899.

JOHN SYME FLEMING. y HENRY FROEHLING.

'Witnessesz S. G. WEBB, Jos. W. HUNDLEY.

IOO

